IT was a busy week in Scottish politics. One would-be opposition leader resigned. (Richard Leonard.) Another left to front the Scottish branch of a rebranded party headed by a man who was recently flogging investment tips for £199 a year. (Michelle Ballantyne and Nigel Farage, respectively.)

But the event that caught my eye over the last seven days had little to do with the machinations on Holyrood’s opposition benches. Last Thursday, cabinet secretary Michael Russell and Irish foreign minister Simon Coveney published a joint report ­setting out a series of bilateral economic and social initiatives agreed by the Scottish and Irish governments.

New arrangements on helping small ­businesses and developing town centres might sound like small beer in the face of the pandemic but they attest to the ­Scottish Government’s quiet success in building ties with it nearest independent ­neighbour. Doubtless behind the scenes officials in Dublin and Edinburgh are also talking about another shared concern: the future of the United Kingdom, and Northern ­Ireland’s place in it.

On the face of it, Irish unification has ­never seemed more likely. This past week was the week in which the reality of ­Brexit really began to be felt. As ­shoppers in Northern Ireland complained of near ­empty shelves in some supermarkets, the ­Democratic Unionist Party’s Ian ­Paisley Junior complained – without a hint of irony – of being “screwed over” by Boris ­Johnson’s government.

The National: Home Secretary Theresa May

It is hard to feel much sympathy for the DUP. The party took £435,000 from an anonymous source to campaign for Brexit then wasted their whip hand over Theresa May to constantly push for the hardest break with the European Union. As if to compound their error, the Unionists then placed all their trust in Johnson, a man of so such probity that the number of his ­offspring is a matter of conjecture.

The result is that Northern Ireland’s place in the Union is up for debate in a way that would have been unimaginable just five years ago. The centenary of Northern Ireland’s founding is accompanied by what, for Unionists, is an existential crisis. The question of a border poll has become when, not if.

Northern Ireland was created with an in-built pro-Union majority. The fledgling Stormont state was two-thirds Protestant. But demographics have changed significantly in the intervening century and there seems to be signs that attitudes are shifting, too: a much-cited Ashcroft poll in late 2019 put support for unification at 51%. Other polls had the union on a “knife-edge.”

No wonder talk about the prospect of Irish unification has grown, on both sides of the border. As we know in Scotland, once you start talking about constitutional change it can be hard to stop.

BUT there are reasons to be circumspect about the prospects of a border poll, at least in the short-term. For one thing what a united Ireland would look like remains nebulous: would Stormont still exist? Would it be a new nation, or would the north simply merge into the south as East Germany did into West after the Berlin Wall fell? A recent academic report recommended that a border poll should not take place until there is a clear plan of what follows.

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“The more you take unification ­seriously, the more you realise how ­complex it is,” SDLP MLA Matthew O’Toole told me recently. “While clearly a border poll is more likely than ­anything since Good Friday Agreement, the ­conversations that need to happen about what it would look like haven’t ­happened.”

While Germany is often cited as the ­example – and Brussels has said that Northern Ireland would also automatically join the European Union – perhaps a closer parallel is Albania and Kosovo. The two Balkan states are ­overwhelmingly ethnic Albanian but have long been ­partitioned.

The largest party in Albanian-­majority Kosovo is the pro-unification ­Vetëvendosje. When I met its ­charismatic leader, Albin Kurti, in Pristina a few years ago he talked up the ­advantages of ­Albanian unity. A few hundred miles south in Tirana, almost every ­political leader supports Kurti’s aims – but stops short of doing anything to make ­unification happen.

The situation in Ireland is similar. ­Pretty much every politician in the Dáil is in favour of unity in principle – but ­almost all would do anything to avoid talking about it in practice. Voters in the Irish Republic seldom show much interest in affairs north of the border. Sinn Fein’s recent southern electoral success owes little to its all-Ireland ambitions, while a Northern Irish border poll campaign headed by the IRA’s political wing would put off non-aligned voters in droves.

Although the Irish Department of ­Foreign Affairs has quietly increased its diplomatic reach in Belfast – ­particularly with Unionists – publicly politicians in Dublin have been wary of being drawn into “the northern question”.

Irish ­Taoiseach Micheál Martin has said that, within the next five years, a border poll is not on his government’s agenda.

But the timing of a unification ­referendum is beyond Martin’s ­control. Under the terms of the Good Friday Agreement, only the Northern Irish ­secretary can mandate a border poll – “if at any time it appears likely to him” that a majority want a united Ireland.

But how Brandon Lewis – or any future secretary of state for that matter – decides whether a vote for unity is “likely” is far from clear.

Polls might give the answer. If there is – as in Scotland – sustained poll leads for unification surely that should trigger a border poll? But, u unlike in Scotland, opinion polling in Northern Ireland is a very imprecise science, and there is ­evidence that the pro-unification vote has been over-estimated.

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In a recent edition of the newly reinstated Belfast-based political magazine ­Fortnight, journalist Marcus Leroux points out that Northern Irish polls have consistently failed to account for non-­voters.

Unlike in other places, these aren’t ­voters who don’t care about politics. They are voters who don’t care about orange and green politics. But when it comes to the constitution what Leroux dubs “scunnered Unionists” break three-to-one against unification.

BUT does that mean the union is safe in Northern Ireland? A former prominent DUP figure told me that he was sanguine about the prospects of a border poll anytime soon but was worried about Unionism’s long-term future.

“Brexit has upset Unionism and energised nationalism but that is not the same as a majority for unification,” he said. “But there has been little talk about how to make Northern Ireland, and the Union, more appealing. That hasn’t happened, and it as to.”

For all the talk of a border poll, this Unionist sees the greatest threat coming from the other side of the Irish Sea: “My sense is that Scotland is in a much more precarious place in the Union than ­Northern Ireland.”

Peter Geoghegan is investigations editor at openDemocracy. The paperback edition of his latest book Democracy for Sale: Dark Money And Dirty Politics was published earlier this month by Head of Zeus